This is a working overview of tuftsin, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-08-03. Anything still debated is marked as such rather than presented as settled.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Consistent with the move away from questions of blame to questions of culture and ideology, American historians have also begun exploring the intersection between domestic U.S. political developments and the early years of Cold War outbreak. One such example is Thomas Borstelmann's 2003 work "The Cold War and the Color Line", which defines domestic racial discrimination after 1945 as a foreign as well as a domestic issue: America’s closest allies against the Soviet Union were colonial powers who had interests that needed to be balanced against those of the emerging 'Third World' in a diverse multiracial, anti-Communist alliance. Domestically, at the same time, U.S. racial reform was essential to preserve the national consensus needed to sustain the Cold War struggle.
"Homo neanderthalensis". The Smithsonian Institution. February 14, 2010. Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016). "Neanderthal DNA". International Society of Genetic Genealogy. Archived from the original on June 17, 2006.: Includes Neanderthal mtDNA sequences GenBank records for H. s. neanderthalensis maintained by the National Center for Biotechnology Information (NCBI) Alex, Bridget (February 21, 2024). "What's Behind the Evolution of Neanderthal Portraits". SAPIENS. The Climate Chronicles, explores the impact of Pleistocene climate change on Neanderthals and other hominins.
The bacterial outer membrane is found in gram-negative bacteria. Gram-negative bacteria form two lipid bilayers in their cell envelopes - an inner membrane (IM) that encapsulates the cytoplasm, and an outer membrane (OM) that encapsulates the periplasm. The composition of the outer membrane is distinct from that of the inner cytoplasmic cell membrane - among other things, the outer leaflet of the outer membrane of many gram-negative bacteria includes a complex lipopolysaccharide whose lipid portion acts as an endotoxin - and in some bacteria such as E. coli it is linked to the cell's peptidoglycan by Braun's lipoprotein. Porins can be found in this layer.
Heteroduplex analysis (HDA) is a method in biochemistry used to detect point mutations in DNA (Deoxyribonucleic acid) since 1992. Heteroduplexes are dsDNA molecules that have one or more mismatched pairs, on the other hand homoduplexes are dsDNA which are perfectly paired. This method of analysis depend up on the fact that heteroduplexes shows reduced mobility relative to the homoduplex DNA. heteroduplexes are formed between different DNA alleles. In a mixture of wild-type and mutant amplified DNA, heteroduplexes are formed in mutant alleles and homoduplexes are formed in wild-type alleles. There are two types of heteroduplexes based on type and extent of mutation in the DNA. Small deletions or insertion create bulge-type heteroduplexes which is stable and is verified by electron microscope. Single base substitutions creates more unstable heteroduplexes called bubble-type heteroduplexes, because of low stability it is difficult to visualize in electron microscopy. HDA is widely used for rapid screening of mutation of the 3 bp p.F508del deletion in the CFTR gene.
Sources: en.wikipedia.org
Problems with mRNA stability have been identified in viral genomes, cancer cells, and various diseases. Research shows that many of these problems arise because of faulty ARE function. Deficiency of the ZFP36 family show that ZFP36 ARE binding proteins are critical regulators of T cell homeostasis and autoimmunity. Deficient mice have also indicated a protective role for ZFP36 ARE binding proteins via regulating cytokine levels in the thymic microenvironment, thereby preventing thymic involution. Additional potential problems have been listed below:
==== Lead replacement ==== The density difference between lead (11.32 g/cm3) and bismuth (9.78 g/cm3) is small enough that for many ballistics and weighting applications, bismuth can substitute for lead. For example, it can replace lead as a dense material in fishing sinkers. It has been used as a replacement for lead in shot, bullets, and less lethal riot gun ammunition. The Netherlands, Denmark, England, Wales, the United States, and many other countries now prohibit the use of lead shot for the hunting of wetland birds, as many birds are prone to lead poisoning owing to mistaken ingestion of lead (instead of small stones and grit) to aid digestion, or even prohibit the use of lead for all hunting, such as in the Netherlands. Bismuth-tin alloy shot is one alternative that provides similar ballistic performance to lead. Bismuth, as a dense element of high atomic weight, is used in bismuth-impregnated latex shields to shield from X-rays in medical examinations, such as CTs, mostly as it is considered nontoxic. The European Union's Restriction of Hazardous Substances Directive for reduction of lead has broadened bismuth's use in electronics as a component of low-melting-point solders, as a replacement for traditional tin-lead solders. Its low toxicity is especially important for solders to be used in food-processing equipment and copper water pipes, although it can also be used in other applications, including those in the automobile industry, in the European Union, for example.
Tolbutamide is a first-generation potassium channel blocker, sulfonylurea oral hypoglycemic medication. This drug may be used in the management of type 2 diabetes if diet alone is not effective. Tolbutamide stimulates the secretion of insulin by the pancreas. It is not routinely used due to a higher incidence of adverse effects compared to newer, second-generation sulfonylureas, such as Glibenclamide. It generally has a short duration of action due to its rapid metabolism, so is safe for use in older people. It was discovered in 1956.
=== Supplements === Dietary supplements of pantothenic acid commonly use pantothenol (or panthenol), a shelf-stable analog, which is converted to pantothenic acid once consumed. Calcium pantothenate – a salt – may be used in manufacturing because it is more resistant than pantothenic acid to factors that deteriorate stability, such as acid, alkali or heat. The amount of pantothenic acid in dietary supplement products may contain up to 1,000 mg (200 times the Adequate Intake level for adults), without evidence that such large amounts provide any benefit. According to WebMD, pantothenic acid supplements have a long list of claimed uses, but there is insufficient scientific evidence to support any of them. As a dietary supplement, pantothenic acid is not the same as pantethine, which is composed of two pantothenic acid molecules linked by a disulfide bridge. Sold as a high-dose supplement (600 mg), pantethine may be effective for lowering blood levels of LDL cholesterol – a risk factor for cardiovascular diseases – but its long-term effects are unknown, so use should be supervised by a physician. Dietary supplementation with pantothenic acid does not have the cholesterol-lowering effect as pantethine.
Le Havre is a major port city in the Seine-Maritime department in the Normandy region of northern France. It is situated on the right bank of the estuary of the river Seine on the English Channel southwest of the Pays de Caux, very close to the Prime Meridian. Le Havre is the busiest port on the northern French Coast and largest container port in France. it is the second largest city in the Normandy region of France with total population of the greater Le Havre conurbation being smaller than that of Rouen. It is also the second largest subprefecture in France, after only Reims. The name Le Havre means 'the harbour' or 'the port'. Its inhabitants are known as Havrais (masculine) or Havraises (feminine). The city and port were founded by King Francis I in 1517. Economic development in the early modern period was hampered by religious wars, conflicts with the English, epidemics, and storms. It was from the end of the 18th century that Le Havre started growing and the port took off first with the slave trade then other international trade. After the 1944 bombings the firm of Auguste Perret began to rebuild the city in concrete. The oil, chemical, and automotive industries were dynamic during the Trente Glorieuses (postwar boom) but the 1970s marked the end of the golden age of ocean liners and the beginning of the economic crisis: the population declined, unemployment increased and remains at a high level today. Changes in years 1990–2000 were numerous.
Sources: en.wikipedia.org
== Tetramerization == p53 initially forms dimers cotranslationally during protein synthesis on ribosomes. Each dimer consists of two p53 monomers joined through their oligomerization domains. The dimerization interface spans residues 325–356 and includes a beta-strand (residues 325–333), a alpha-helix (residues 335–356), and a sharp turn at the conserved hinge residue Gly334. This configuration links the beta-strand and alpha-helix to form a V-shaped monomer topology. The beta-strand contributes to the formation of an antiparallel intermolecular beta-sheet between two p53 monomers, stabilized by hydrophobic interactions involving Phe328, Leu330, and Ile332. The alpha-helix forms an antiparallel coiled-coil between the two monomers, with a packing angle of 156°. Helix–helix interactions are stabilized by hydrophobic contacts (e.g., Phe338, Phe341, Leu344) and electrostatic interactions, such as the Arg337–Asp352 salt bridge. Following dimer formation, p53 dimers associate posttranslationally to form tetramers (dimers of dimers). The tetramerization domain (residues 325–356) plays a central role in stabilizing the tetrameric structure. In the tetramer, the two primary dimers associate at an angle described as "roughly orthogonal," with a helix bundle packing angle (θ) of approximately 80°. Tetramers represent the active form of p53 for DNA binding and transcriptional regulation.
=== Products === PFAS are used to produce fluoropolymers by emulsion polymerization. Because they resist heat, oil, stains, grease, and water, they are ingredients in stain repellents, polishes, paints, and coatings. They came into use with the invention of Teflon in 1938. They have been used in products including waterproof fabric such as nylon, yoga pants, carpets, shampoo, feminine hygiene products, mobile phone screens, wall paint, furniture, adhesives, food packaging, firefighting foam, the insulation of electrical wires, dental floss and sunscreen. PFAS have been used by the cosmetic industry in cosmetics and personal care products, including lipstick, eye liner, mascara, foundation, concealer, lip balm, blush, and nail polish. Pesticides including fluazinam and flufenacet break down to produce trifluoroacetic acid. In 2025, a report by the US FDA stated that in 2021, up to 1.4% of cosmetics sold in Europe contained PFAS and as of 2025, less than 1% of cosmetics sold in the US contained PFAS.
== Early views == In the 4th century BC, the Greek philosopher Plato argued that love directs the bonds of human society. In his Symposium, Eryximachus, one of the narrators in the dialog, states that love goes far beyond simple attraction to human beauty. He states that it occurs throughout the animal and plant kingdoms, as well as throughout the universe. Love directs everything that occurs, in the realm of the gods as well as that of humans (186a–b). Eryximachus reasons that when various opposing elements such as wet and dry are "animated by the proper species of Love, they are in harmony with one another... But when the sort of Love that is crude and impulsive controls the seasons, he brings death and destruction" (188a). Because it is love that guides the relations between these sets of opposites throughout existence, in every case it is the higher form of love that brings harmony and cleaves toward the good, whereas the impulsive vulgar love creates disharmony. Plato concludes that the highest form of love is the greatest. When love "is directed, in temperance and justice, towards the good, whether in heaven or on earth: happiness and good fortune, the bonds of human society, concord with the gods above—all these are among his gifts" (188d). In the 1660s, the Dutch philosopher Spinoza wrote, in his Ethics of Human Bondage or the Strength of the Emotions, that the term bondage relates to the human infirmity in moderating and checking the emotions.
== Function == A nerve conveys information in the form of electrochemical impulses (as nerve impulses known as action potentials) carried by the individual neurons that make up the nerve. These impulses are extremely fast, with some myelinated neurons conducting at speeds up to 120 m/s. The impulses travel from one neuron to another by crossing a synapse, where the message is converted from electrical to chemical and then back to electrical.
== Contraindications == The safety of methenamine in people with renal impairment is unknown and it is considered to be contraindicated in this context. Other contraindications include severe liver disease or hepatic impairment, known hypersensitivity to methenamine or the drug formulation's components, severe dehydration, hyperphosphatemia, and use of sulfonamides. Caution is also advised in people with gout. Its safety during pregnancy is unclear and it is known to enter the placenta, amniotic fluid, and breast milk. As such, discontinuation of methenamine is recommended during breastfeeding. No teratogenic effects with methenamine in animals have been observed. Although the preceding contraindications of methenamine have been specified, they are not well-defined and may not be absolute contraindications in all cases.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.